1. Field of the Invention
This invention relates to a disc cartridge, and more particularly to a disc cartridge which is adapted to rotatably receive a disc medium such as an optical disc, a photo-magnetic disc, a magnetic disc, a floppy disc or the like therein.
2. Description of the Prior Art
In general, a disc cartridge such as a tray system or a cartridge system using a casing has been conventionally employed for protecting a floppy disc, a compact disc, a video disc or the like which is used for a digital-data storing unit, a video unit or the like from damage and dust to ensure its safety.
For this purpose, the conventional disc cartridge, as shown in FIGS. 1 to 3, is provided with a slidable shutter 200 which is adapted to close a pickup inserting hole 202 and/or a drive pin inserting hole (not shown) of a casing 204 in nonuse and open them in use. The pickup inserting hole 202 is provided for inserting a pickup of a disc cartridge operating unit such as a recording and/or reproducing unit (hereinafter referred to as "cartridge operating unit") therethrough into the casing.
In the so-constructed conventional disc cartridge, when the shutter 200 is formed into an elongated shape, a holding plate 206 is used for guiding a distal end of the shutter 200 in a recess 208 of the casing 204. Mounting of the holding plate 206 with respect to the casing 204 is carried out using any adhesive means 210 such as an adhesive or a double-coated adhesive tape applied with respect to a half of a width of a rear surface of the holding plate 206 in a longitudinal direction thereof. Unfortunately, this has a negative effect on the operating efficiency in assembling of the disc cartridge, because an operation to apply the adhesive means 210 to the holding plate 206 or casing 204 is required. Also, this requires the holding plate 206 to be large because the holding plate is required to have a width sufficient to facilitate mounting of it on the casing 204 through the adhesive means, resulting in the disc cartridge being large and costly. Further, misregistration of the holding plate 206 with respect to the shutter 200 in the operation of mounting the holding plate 206 on the casing leads to contact between the adhesive means 210 and the shutter 200 to deteriorate smooth actuation or operation of the shutter.
Accordingly, it would be highly desirable to develop a disc cartridge which is capable of readily mounting a holding plate on a casing without using any adhesive means while ensuring smooth operation of a shutter.